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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #153708
Title: FINDING QTL FOR CARCASS TRAITS

Author
item Macneil, Michael
item GROSZ, M - GENOMIX
item French, Larry

Submitted to: Research Update for Fort Keogh Livestock and Range Research Laboratory
Publication Type: Popular Publication
Publication Acceptance Date: 10/1/2002
Publication Date: 1/15/2003
Citation: MACNEIL, M.D., GROSZ, M.D., FRENCH, L.B. FINDING QTL FOR CARCASS TRAITS. RESEARCH UPDATE FOR FORT KEOGH LIVESTOCK AND RANGE RESEARCH LABORATORY. p. 59. 2003.

Interpretive Summary: Development of saturated genetic marker maps allows identification of quantitative trait loci (QTL) affecting traits of economic importance. Genome-wide scans are preliminary investigations that can lead to fruitful studies to confirm and localize QTL. Identifying QTL and closely linked markers has potential to significantly increase the rate of genetic improvement through implementation of marker assisted selection. The objective of this research was to identify genomic intervals which contain genes affecting carcass traits at a constant fat depth endpoint. We were successful in identifying QTL influencing live weight, carcass weight, dressing percentage, ribeye area, and fat deposition and thus affecting USDA Quality and Yield Grades. Results of this research serve as a guide to future studies to confirm the presence of QTL in the identified regions and to refine their location.

Technical Abstract: A genome-wide scan for chromosomal regions influencing carcass traits was conducted spanning 2.497 Morgans on 29 bovine autosomes using 170 microsatellite markers. There were 151 progeny from a single Hereford x composite bull produced by backcross matings to both Hereford and composite dams. Cattle were fed out and slaughtered serially over 13 wk when they were between 614 and 741 d of age. Phenotypes measured at harvest were: carcass weight; slaughter weight; fat depth; marbling; percentage kidney, pelvic, and heart fat (KPH fat); and longissimus muscle area. Dressing percentage and USDA Yield Grade were calculated from these data. Analysis of covariance was used to adjust these phenotypes to a constant fat depth. Residuals from the analysis of covariance were analyzed by interval mapping to detect putative QTL. Nominal significance was established by permutation analysis. Approximate genome-wide significance levels were established by applying the Bonferroni correction to the nominal probability levels. At a constant fat depth, putative QTL were detected affecting live weight on BTA 12, BTA 17, and BTA 18; dressing percent on BTA 16 and BTA 24; longissimus muscle area on BTA 12; KPH fat on BTA 15, BTA 17, and BTA 20; USDA Yield Grade on BTA 12; marbling score on BTA 2, BTA 14, BTA 18, and BTA 26. These results indicate new promising locations for QTL segregating in Bos taurus that affect carcass traits. Greater marker saturation in these regions coupled with refined methods for data analysis will lead to more precise determination of QTL positions.